Methods of making smooth reinforced cementitious boards

ABSTRACT

A composite fabric for use in reinforcement of cementitious boards and similar prefabricated building wall panels. The fabric includes an open mesh first component of continuously coated, high modulus of elasticity strands and a nonwoven second component fabricated from alkali resistant thermoplastic material. The high modulus strands of the first component are preferably bundled glass fibers encapsulated by alkali and water resistant thermoplastic material. The composite fabric also has suitable physical characteristics for embedment within the cement matrix of the panels or boards closely adjacent the opposed faces thereof. The reinforcement provides long-lasting, high strength tensile reinforcement and impact resistance for the panels or boards. The reinforcement also enables the boards to have smooth outer faces suitable for painting, papering, tiling or other finishing treatment. Included as part of the invention are methods for making the reinforcement, cementitious boards and panels including the reinforcement, and methods for manufacturing such boards and panels.

CROSS-REFERNCE TO RELATED APPLICATIONS

[0001] This application is a divisional of pending U.S. patentapplication Ser. No. 10/155,650 entitled METHODS OF MAKING SMOOTHREINFORCED CEMENTITIOUS BOARDS, filed May 23, 2002, which is adivisional of pending U.S. patent application Ser. No. 09/478,129entitled SMOOTH REINFORCED CEMENTITIOUS BOARDS AND METHODS OF MAKINGSAME, filed Jan. 5, 2000.

FIELD OF THE INVENTION

[0002] The present invention relates in general to reinforced productsand in particular to reinforced cementitious boards for buildingconstruction and methods of making such boards.

BACKGROUND OF THE INVENTION

[0003] Dry wall or gypsum board is commonly used in the erection ofinterior walls in commercial, residential and other building structures.Dry wall is effective when used to enclose rooms subject to normalhumidity and surface moisture conditions that occur in many of the roomscommonly found in offices, shops, residences and other buildings.However, bathrooms, basements and certain areas of residential andcommercial kitchens may pose potential moisture problems for interiorwalls constructed from dry wall wallboard.

[0004] When dry wall is used in bathrooms, for example, tile may beadhered directly to the dry wall. Alternatively, some bathrooms utilizeprefabricated modular stalls and/or bathtubs which may be adhered to thedry wall in the bathing areas of the room. Because hot baths and,especially, hot showers produce steam, bathrooms are frequently exposedto periods of very high humidity. Additionally, the basins and bathingareas thereof are susceptible to localized collection of surfacemoisture in the form of small pools or puddles of water. If cracks arepresent in the tile grout or if the seams between the dry wall and thebasins or prefabricated bathing area components are not completelysealed, the steam or puddled surface water may come into contact withthe dry wall.

[0005] The opposed faces of dry wall are typically covered with paperwhich is suitable for receiving paints, primers and tile adhesives.However, such paper also has a tendency to absorb water. As the water isabsorbed by the paper, it comes into contact with the gypsum core of thedry wall. Gypsum is a hygroscopic material. The gypsum core thereforeabsorbs moisture that passes through the facing paper. Over the courseof time the level of water absorption may degrade the structuralintegrity of the dry wall board. If the water damage becomes excessive,some or all of the board may require replacement, which may be anespecially laborious task in the bathing areas of a bathroom.

[0006] Because they are effectively immune to water damage, cementitiousboards have been employed as alternatives to dry wall in particularlyhumid and wet rooms. Cementitious boards may be fabricated to assumeessentially the same dimensions and weight, as well as support the samesorts of facing materials, as conventional dry wall. As is known,concrete and similar cementitious materials have far greater compressivestrength than tensile strength. This phenomenon mandates thatcementitious boards and similar, relatively thin, panel-likecementitious objects be handled with care during transport. Morespecifically, unless sufficiently reinforced such boards must be carriedsubstantially vertically, i.e., with their opposed faces extendingsubstantially perpendicularly to the ground or floor surface. This isespecially true in the case of approximately {fraction (1/4)} inch thickboards that are typically laid over a plywood or particle boardsubstrate and used to provide a smooth backing for receiving vinyl, tileor other flooring or countertop coverings. If carried substantiallyhorizontally, i.e., with the opposed board faces extending substantiallyparallel to the ground surface such as would occur if opposite end edgesor opposite side edges of the board are supported by two or moreworkers, the material in the upper regions of the board (in thethickness dimensions of the board) would be in compression and thematerial in the lower regions of the board would be in tension. If thetensile forces exceed the tensile strength of the cementitious material,the board may snap during transport. Alternatively, although lessovertly catastrophic, radiant cracking may occur in the lower regions ofthe board which may preclude its installation or, if installed, mightgreatly comprise its bearing capacity and service life. Moreover,reinforcement should be of sufficient durability that it continues tostrengthen and toughen the board over the typical projected 2040 yearservice life of the board.

[0007] Various means have been proposed for reinforcing cementitiousboards. Typically, the reinforcement comprises an open grid structurewhose central plane is embedded approximately {fraction (1/32)} to{fraction (1/16)} inch beneath each face of the ordinarily ½ to{fraction (5/8)} inch thick wall board or the {fraction (1/4)} inchbacking board for vinyl, tile or other flooring or countertop coverings.For example, open mesh woven polypropylene has been used for thispurpose because of its resistance to water and the alkaline chemistriesof Portland cement concrete and similar cementitious materials. However,because of the comparatively low modulus of elasticity of polyolefinssuch as polypropylene and polyethylene, which is on the order of about10,000 to about 75,000 psi, such materials experience high strain underthe tensile loads which can occur due to improper handling of thecementitious board. As tensile reinforcement, therefore, polypropylenegrids are of limited practical use.

[0008] High modulus of elasticity materials have also been proposed foruse as reinforcement for building panels. U.S. Pat. Nos. 5,552,207 and5,763,043, for example, describe wall facings comprising an open grid,resin impregnated, fiberglass fabric which is affixed to a rigid foaminsulation board and covered by and embedded within stucco orstucco-like material. The wall facing may be prepared either in situ onthe outside of a building or in the form of prefabricated panels whichmay be bonded to a building wall. The wall facing, including theprefabricated panel embodiments thereof, is attached to a pre-existingwall and is not itself used as a wall panel in the manner, for example,of dry wall or the cementitious boards of the present invention. Indeed,the wall facing may be affixed to dry wall or cementitious boards butcannot be used in lieu thereof because of the low bending strength ofits plastic foam backing board. A wall constructed solely of such facingwould likely be destroyed as a result of minor impacts there against,including the sorts of impacts routinely absorbed by dry wall andcementitious wall panel boards. Because of the rough-textured finish andthorough coverage afforded by the stucco material, comparatively heavyand inexpensive fiberglass yarns arranged at an average of 3 to 10 endsper inch are used for the rovings or yarns.

[0009] As noted hereinabove, the reinforcement provided in existingcementitious boards is typically embedded just beneath each face of theboards. By locating the reinforcement so close to the surface of theboard faces, the tensile stress transfer from the concrete to thereinforcement is optimized. It is the concrete material which is closestthe board faces, i.e., the “skin” concrete, that is potentially subjectto the greatest tensile forces and, therefore, in greatest need oftensile stress relief due to improper handling of the board. Ifreinforcement is embedded much more deeply than about {fraction (1/16)}inch beneath the board faces, the reinforcement becomes situated tooclose to the neutral axis of the board. Hence, the flexural modulus ofthe board is thus reduced, and the board becomes more flimsy and proneto surface cracking. By maintaining the reinforcement close to the boardfaces, the board is stiffened in much the same way that the parallelflanges strengthen an I-beam.

[0010] Vinyl coated glass fiber mesh is disclosed as a reinforcement forcementitious boards in U.S. Pat. Nos. 4,793,892 and 4,816,091.Relatively light and heavy weight glass fabrics are disclosed asalternative reinforcement materials. For instance, somewhat heavy 8×8 or10×10 yarn per inch fiberglass meshes are disclosed in one embodiment toprovide openings of a size sufficient to permit passage of the board'scementitious core material and thereby enable good mechanical interlockbetween the reinforcement and the core material. From an aestheticperspective, comparatively thick, open 8×8 or 10×10 yarn per inchfiberglass reinforcement meshes produce a rough board face. Forconsumers who desire smooth wall surfaces for painting, papering, tilingand the like, the peaks and valleys produced by such fabrics, especiallyat the warp and weft strand intersections, would be unacceptable. Thesepatents also disclose another embodiment wherein lighter weight 20×12 or16×12 glass fiber woven mesh may be used as the reinforcement. Thisalternative, although presenting a smoother board face, nevertheless isvery expensive because lighter fiberglass yarns are more costly perpound and tighter fabrics require more time and cost to produce thanboard reinforced with heavier fabrics.

[0011] Cellulose reinforced cementitious boards having smooth surfacesare also known. However, these building products exhibit less structuralstrength and water and alkali resistance than cementitious boardsreinforced with high modulus materials such as suitably coated glassfiber or the like.

[0012] A need exists, therefore, for high modulus reinforcement forcementitious boards and similar construction panels which is highlyresistant to alkali and water attack, comparatively low in cost andallows one or both of the board's oppositely facing surfaces to have asmooth finish suitable for painting, papering, tiling or otherdecorative treatment.

[0013] Further advantages exist for reliable methods for manufacturingsuch reinforcement, boards incorporating the reinforcement and methodsfor manufacturing such boards.

SUMMARY OF THE INVENTION

[0014] The present invention provides a composite fabric for use inreinforcement of cementitious boards and similar prefabricated buildingwall panels. The composite fabric comprises a continuously coated, highmodulus of elasticity mesh first component and a nonwoven secondcomponent. The high modulus strands of the first component preferablycomprise glass fibers encapsulated by alkali and water resistant polymerand arranged at no greater than about 15 ends per inch in the machineand cross-machine directions of the material. The nonwoven secondcomponent is preferably a thin web of randomly oriented, water andalkali resistant fibers. The composite fabric is relatively easy andinexpensive to manufacture and incorporate into cementitious boards.Significantly, it has physical characteristics that enable its embedmentwithin the cement matrix of the panels or boards closely adjacent one orboth of the opposed faces thereof to provide the boards with smoothouter surface(s) suitable for painting, papering, tiling or otherdecorative finishing treatment. The fabric provides long-lasting, highstrength tensile reinforcement of the panels or boards regardless oftheir spatial orientation during handling and use. The reinforcementalso enhances the impact resistance of the boards after installation.

[0015] Included as part of the invention are methods for making thereinforcement, cementitious boards and panels including thereinforcement, and methods for manufacturing such boards and panels.

[0016] Other details, objects and advantages of the present inventionwill become apparent as the following description of the presentlypreferred embodiments and presently preferred methods of practicing theinvention proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The invention will become more readily apparent from thefollowing description of preferred embodiments thereof shown, by way ofexample only, in the accompanying drawings wherein:

[0018]FIG. 1 is a cross-sectional view through the thickness of acementitious board constructed in accordance with the present invention;and

[0019]FIG. 2 is a schematic elevation view of an apparatus suitable forconstructing a cementitious board according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0020] Referring initially to FIG. 1, there is shown a cementitiousboard or panel 10 constructed according to the present invention. Board10 is substantially planar and has opposed faces 12 and 14 and thickness“T” typically of about {fraction (1/2)} inch to about {fraction (5/8)}inches for wall boards, although boards as thin as {fraction (1/4)} inchmay be constructed for use primarily as backing for tile, vinyl or otherfloor or countertop coverings. Board 10 may be manufactured to anyperipheral or areal dimensions, e.g., the eight-foot length by four-footwidth common to dry wall boards. At the job site board 10 may be cut toany desired size or shape by hand by scoring and snapping the scorededge, or by a power saw.

[0021] Board 10 comprises cementitious matrix material 16 such asPortland cement concrete or other hydraulic concrete which is reinforcednear at least one or, more preferably, both of opposed faces 12 and 14with reinforcement 18 constructed in accordance with the presentinvention. It is especially advantageous to reinforce board 10 adjacentboth of faces 12 and 14. In that way, should the board 10 be carried byworkers in the generally horizontal disposition of FIG. 1, i.e., withthe opposed board faces 12, 14 extending substantially parallel to theground or floor surface, there will be high modulus tensilereinforcement in the cementitious matrix material 16 in the lowerregions of the board 10 regardless of whether face 12 or face 14 isdownwardly directed toward the ground or floor surface Additionally,reinforcement disposed closely adjacent the faces of the board maximizesthe flexural strength of the board when in service. To optimize thetensile reinforcement capabilities of reinforcement 18 and avoidspalling of the skin concrete adjacent faces 12 and 14, the centralplane of fabric 18 should be embedded a depth “D” of about {fraction(1/32)} to {fraction (1/16)} inch from face(s) 12,14.

[0022] Reinforcement 18 is a composite fabric comprising a firstcomponent 20 and a second component 22. First component 20 may be awoven knit or a laid scrim open mesh material having mesh openings of asize suitable to permit interfacing between the skin and corecementitious matrix material 16 of board 10. According to a presentlypreferred construction, first component 20 can assume, for instance, agrid-like configuration having a strand count of between about 2 toabout 15 strands per inch in each direction, preferably about 4 to about10 strands per inch. The mesh of first component 20 is preferablycomprised of yarns or rovings having high modulus of elasticity corestrands impregnated and preferably sheathed by a coating of water andalkali-resistant polymer coating. The yarns or rovings of firstcomponent 20 preferably comprises a bundle of fibers having a Young'smodulus of elasticity of at least about 1,000,000 psi such as polyamidefibers of poly(p-phenylene terephthalamide), known as KEVLAR®. Morepreferably, the rovings of first component 20 comprise a bundle ofcontinuous filament “E” or “C” glass fibers having a linear density ofabout 33 to about 300 tex. Because of the presence of water and alkaliin cementitious environments, glass fibers or similar glass core strandmaterials, in the absence of a protectant coating or sheathing, wouldfail in weeks or months rather than the 20 to 40 year service life thatis required for practical deployment of a cementitious board. Thecoating may be provided by any suitable process heretofore known in theart and does not form a part of the present invention.

[0023] For instance, the coating may be a continuous coating of waterand alkali-resistant polymeric material which may be applied by anyconventional spray or dip-coating procedures. Alternatively, the coatingmay be co-extruded with the rovings of the first component 20 in amanner similar to that described in U.S. Pat. No. 5,451,355. Byco-extruding a sheath with the rovings of the first component 20, thecore strand is continuously coated at the moment of its manufacture.

[0024] Preferred sheath materials for the sheath or coating include,without limitation, olefins, polyolefins and olefin copolymers such aspolypropylene and polyethylene, copolymers of polybutylene andpropylene, ethylene propylene rubber (EPR), thermoplastic polyolefinrubber (TBR), polyvinyl chloride compounds, polyvinylidene chloride(SARAN®), ethylene-propylene diene monomer (EPDM) and copolymers ofstyrene and butadiene (SBR).

[0025] When constructed as a co-extruded yarn, the yarns of the firstcomponent 20 may be woven, knitted or cross-laid by any known techniquesto produce a desired open mesh. Following formation of the desired meshfrom the yarns, the mesh may be heated to a temperature to fusethermoplastic sheaths of intersecting yarns at the intersection areasthereof to affix and stabilize the yarns within the fabric.Alternatively, the yarns of the mesh fabric first component 20 may bestitched, adhesively attached or otherwise attached at theirintersection areas by any suitable technique known in the art.

[0026] Another yarn or roving useful in the formation of the mesh firstcomponent 20 includes a core strand of high modulus fibers identical orsimilar to those mentioned above. Unlike the previously describedsheath, however, which provides a continuous, imperforate coating of thecore strand at the moment of manufacture, the alternative sheath ispreferably constructed as a fibrous covering which is spun or otherwisewrapped about the core strand. Suitable apparatus for fabricating such ayarn or roving include the DREF-2 and DREF-3 friction spinning apparatusmanufactured by Fehrer AG of Linz, Austria.

[0027] The DREF-3 apparatus is preferred because the yarn producedthereby comprises a fibrous core sliver commingled with a core strandand covered by sheath. The core sliver may comprise any suitablethermoplastic material including, without limitation, either isotacticor syndiotactic polypropylene, ethylene-propylene copolymers or otherolefinic fibers, nylon, polyvinyl chloride, or polyester, althoughpolyolefins are preferred because of the physical durability and alkaliresistance. Hence, because of its intimate contact with the core strand,the core sliver provides the core strand with alkali resistance andruggedness generally superior to core strands covered merely withsheath. The sheath is preferably fabricated from thermoplastic fibrousmaterials the same as or similar to either the core sliver or the sheathmaterials of the co-extruded yarn described hereinabove.

[0028] By virtue of its fibrous nature, the sheath of a yarn or rovingproduced by the DREF-3 apparatus is not entirely imperforate and thuspossesses some pores which extend the outer periphery of the yarn to thecore strand. However, the composite yarn is substantially more suppleand flexible than the previously described co-extruded yarn and may bemore readily woven, knitted or cross-laid into a desired open meshstructure. Following formation, the mesh is heated to a temperaturesufficient to fuse or sinter the fibers of the sheath such that theymerge into an agglomerated, continuous, imperforate mass encapsulatingthe core strand. Concurrently, the rovings or yarns become fused attheir intersections.

[0029] Although not illustrated, alternative mesh first components 20are contemplated to be within the scope of the present invention. Forexample, a suitable mesh may incorporate co-extruded composite yarns inthe warp or machine direction of the fabric and fiber covered compositeyarns or rovings may be provided in the weft or cross-machine directionof the fabric, or vice versa. Thereafter, the “mixed” yarns may beheated after mesh formation to produce a reinforcement structure ofcontinuously coated and united high modulus strands.

[0030] Second component 22 is a thin, porous, nonwoven materialpreferably fabricated from randomly oriented fibers of water and alkaliresistant, preferably thermoplastic, material. Although thermoplasticsare preferred, non-thermoplastic cellulosic fibers such as cotton,rayon, ramie, flax, sisal, hemp or wood pulp may also be used. Whilecellulosic fibers may not have optimum alkali resistance, they arehydrophilic and thus reduce or eliminate the need for the wetting oradhesion enhancing treatments described below. Water and alkaliresistant thermoplastics are preferred, however, because of theirsuperior ability to withstand the high alkalinity of hydraulic concretesand long-term exposure to moist environments. Although nylons andpolyesters may be used, preferred thermoplastics suitable for use assecond component 22 include spunbonded or carded webs of olefins,polyolefins and olefin copolymers such as polypropylene andpolyethylene, copolymers of polybutylene and propylene, ethylenepropylene rubber (EPR), thermoplastic polyolefin rubber (TBR),polyvinylidene chloride (SARAN®) and ethylenepropylene diene monomer(EPDM).

[0031] The first and second components 20, 22 of composite fabricreinforcement may be stitched, adhesively fixed, heat fused or otherwiseunited with one another by any means or methods commonly employed in theart. For instance, web second component 22 may be coated on one sidewith a conventional inexpensive water-based glue and then brought intocontact with the mesh first component 20. Light to moderate heat and/orpressure may be used to quicken and enhance the bonding process.Alternatively, especially when at least one of the first and secondcomponents 20, 22 contains a thermoplastic, the second component may befused with the first component 20 either during or after the gridcoating and intersection fixing heating steps described above. Stillfurther, the first and second components may be united with one anotherusing known insertion methods and apparatus whereby the web 22 becomesintegrated into the mesh 20, or vice versa. In the case where compositefabric reinforcement 18 is constructed as abutting layers, secondcomponent 22 should be the outermost layer as depicted in FIG. 1.

[0032] In development of the present invention, it has been observedthat the surface finish and integrity of a cementitious 30 boardincorporating composite fabric reinforcement 18 are considerablyimproved if at least one or, more preferably, both the first component20 and second component 22 are treated in a manner so as to enhance atleast one of the wetting and adhesion characteristics thereof. Suchtreatment may be performed before or after the first and secondcomponents 20,22 are united. Treatments may include corona or electricaldischarge treatments to oxidize the surfaces of the first and/or secondcomponents. Alternatively, the first and/or second components may becoated with one or more surfactants, hydrophilic compounds, foamboosters/stabilizers and polar polymer topical solutions such aspolyvinyl alcohol to enhance adhesion and promote continuity of cementslurry about the reinforcement when the reinforcement is later embeddedin cementitious matrix material.

[0033] In addition, cement powder may be slurried with one or morehydrophilic additives, wetting agents, foaming agents and foam boostersand applied to either or both of the first and second components 20,22.Following application, the coated reinforcement is immediately dried toprevent significant reaction of the cement with water (i.e., hydrating)that might otherwise cause the reinforcement to stiffen and resistrolling. A polymer may also be included in the slurry to assure that thecement powder remains bound to the reinforcement fibers and does notflake off after drying. An advantage to this type of pretreatment isthat it imbues the reinforcement with cementing properties and avoidsthe need to pretreatment of the reinforcement with cement slurry on thecement board assembly line.

[0034] If desired, the nonwoven web second component 22 may befabricated from loose fibers that are joined by a chemical binder.Depending on the composition or nature of the fibers, e.g., carded webs,the fibers and the binder chosen to join the fibers may have varyingdegrees of hydrophilicity. Thus, selection of appropriate fibers and/orhydrophilic binder may reduce or even eliminate the need for subsequentwetting and adhesion enhancing treatments on the second component 22.

[0035] The comparatively open mesh first component 20 and nonwoven websecond component 22, when united and embedded in a cementitious boardpromote penetration of cement slurry yet resist pin-holes or roughnesswhich would mar the board faces 12, 14. Additionally, while employingtwo distinct fabrics, composite fabric reinforcement 18 is lessexpensive to manufacture than a single denser mesh of lighter weightglass yarns, e.g., about 20×20 ends per inch, that would be needed toproduce comparable slurry penetration and board surface smoothness.

[0036] Referring to FIG. 2, there is shown an apparatus 24 suitable formanufacturing a reinforced cementitious board having the generalconstruction of board 10 shown in FIG. 1. Apparatus 10 is operable forcontinuous production of a cementitious ribbon or strip suitable forcutting into individual panels or boards of desired length. Apparatus 24dispenses a continuous length of carrier or release paper 26 from aspool, roll or similar supply 28 onto a moving endless conveyor belt 30entrained about a roller 32 and second unillustrated roller at least oneof which is rotatably driven. A first continuous length of compositefabric reinforcement 18 according to the present invention issimultaneously dispensed from a spool, roll or similar supply 34 anddelivered to conveyor belt 30. The carrier paper 26 supports the firstlength of reinforcement 18 as it is drawn through apparatus 24 byconveyor belt 30.

[0037] As an alternative to treating one or both of the first and secondcomponents 20, 22 of reinforcement substantially at their time ofmanufacture, such components may be treated to enhance their wetting andadhesion characteristics as an in-line step of the reinforced boardmanufacturing process. That is, as indicated in FIG. 2, reinforcement 18may first be sprayed or treated at a suitable pretreatment station 36 atwhich preferably both sides of the reinforcement are treated to enhancethe wetting and/or adhesion characteristics thereof. Treatment atstation 36 may include any of the corona or electrical dischargetreatments or surfactant, hydrophilic compound, foam booster/stabilizeror polar polymer topical coating processes enumerated above.

[0038] Upon reaching the conveyor belt 30, reinforcement 18 is moved bythe belt under a hopper 38 where cementitious matrix material 16 isdischarged onto the reinforcement by known means such as a rotatingdispensing device 40. The matrix material is then spread into a uniformlayer as it passes under screed means 42 and, preferably vibrating,compaction roller 44 and between unillustrated side rails. Although notillustrated, it will be understood that, if necessary, reinforcement 18may first be passed through hydraulic cement slurry to assure goodpenetration of the reinforcement 18 with the slurry prior to receipt ofthe cementitious matrix material.

[0039] The process thus far described would be sufficient for embeddingreinforcement 18 adjacent one of the faces 12, 14 of board 10 (FIG. 1).However, it is normally desirable to reinforce a cementitious boardadjacent both its faces. Accordingly, a second continuous length ofcomposite fabric 18 may be deposited on the mass of cementitious matrixmaterial 16 following compaction by roller 44. The second length offabric 18 may be dispensed from a second spool, roll or similar supply46. If desired, the fabric dispensed from supply 46 may be treated at atreatment station 48 preferably identical or substantially similar tostation 36 to enhance the wetting and adhesion characteristics thereof.Additionally, the second length of composite reinforcement 18 may alsobe passed through hydraulic cement slurry to assure good penetration ofthe reinforcement with the slurry prior to placement of thereinforcement onto the uncured matrix material 16. Following placementof the second length of reinforcement 18, the moving strip 0.50 isdesirably compacted by a second, preferably vibrating, compacting roller52. The uncured, reinforced cementitious strip can then be cut byunillustrated means into individual boards or panels and stacked forcuring. In the alternative, apparatus 24 may include an in-line curingstation for hardening the strip 50 after which the cured strip may becut into boards 10 (FIG. 1).

[0040] Although the invention has been described in detail for thepurpose of illustration, it is to be understood that such detail issolely for that purpose and that variations can be made therein by thoseskilled in the art without departing from the spirit and scope of theinvention except as it may be limited by the claims.

What is claimed is:
 1. A method of making a reinforced hydraulic cementcementitious board having first and second faces, said method comprisingthe steps of: selecting composite fabric reinforcement comprising anopen mesh first component of high modulus of elasticity fiber strandscontinuously covered with alkali resistant polymeric material and anonwoven web second component; treating at least one of said first andsecond components to enhance at least one of wetting and adhesioncharacteristics thereof with respect to hydraulic cement when saidreinforcement is embedded therein; and embedding said reinforcement inhydraulic cement cementitious matrix material.
 2. The method of claim 1wherein said polymeric material is thermoplastic material.
 3. The methodof claim 1 wherein said second component is fabricated fromthermoplastic material.
 4. The method of claims 2 or 3 wherein saidthermoplastic material is selected from the group consisting of olefins,polyolefins, olefin copolymers, polypropylene, polyethylene, ethylenepropylene rubber, thermoplastic polyolefin rubber, polyvinylidenechloride, polyvinyl chloride compounds, ethylene-propylene dienemonomer, copolymers of polybutylene and propylene, and copolymers ofstyrene and butadiene.
 5. The method of claim 1 wherein said mesh has astrand count of about 2 to about 15 strands per inch in each direction.6. The method of claim 1 wherein said strands comprise bundled glassfibers having a linear density of about 33 to about 300 tex.
 7. A methodof making cementitious boards comprising the steps of: providing an openmesh first component of high modulus of elasticity fiber strands coveredwith alkali-resistant polymeric material; providing a nonwoven websecond component; treating at least one of said first and secondcomponents to enhance at least one of wetting and adhesioncharacteristics thereof with respect to hydraulic cement cementitiousmatrix material; uniting said first and second components; and embeddingthe united first and second components in hydraulic cement cementitiousmatrix material.
 8. A method of making cementitious boards comprisingthe steps of: providing an open mesh first component of high modulus ofelasticity fiber strands covered with alkali-resistant polymericmaterial; providing a nonwoven web second component; uniting said firstand second components; treating at least one of said first and secondcomponents to enhance at least one of wetting and adhesioncharacteristics thereof with respect to hydraulic cement cementitiousmatrix material; and embedding the united first and second components inhydraulic cement cementitious matrix material.